A classification of ash which arises on the incineration of waste, for example industrial waste or domestic waste, is generally known. Classification is understood as a separation of a starting material comprising particles having a given grain size distribution into a plurality of fractions of different grain size distributions. The classification in particular serves to separate the ash into portions differently charged with specific contaminants, with some portions being able to be profitably recycled, while other portions have to be landfilled while incurring costs due to the existing relevant statutory regulations. A classification can utilize the generally known circumstance that specific contaminants essentially only bind ash particles having a specific maximum grain size.
Despite this knowledge, it has previously not been possible to process incinerator bottom ash in an economically interesting manner while observing statutory provisions. The incinerator bottom ash is rather usually landfilled in practice, which is, however, associated with relatively high costs, or it is utilized subject to high constraints, e.g. as a low-classification building material.